Heretofore, there have been various systems using a data search scheme. For example, a call center assistance system is one example of such systems. In the call center assistance system, query and response data such as mails about diversified inquiries, which have been handled in the past, are stored as operations records in a database. A person in charge at the call center is required to answer by retrieving a suitable reply to a query from a user as soon as possible, while searching for past referential data without regard to skill and knowledge. However, doing so is difficult for a person in charge without skill and knowledge, as a huge amount of inquiry data and response data is stored in a database.
When a person in charge retrieves referential data from past operations records, a method of selecting a suitable keyword and performing a search is conceivable. By carrying out a search using a keyword, a person in charge can reply to a query from a user more rapidly. However, a person in charge must have skill and knowledge to select a suitable keyword. In view of such a problem, for example, in Patent Literation 1, carrying out a data search without selecting a keyword is made feasible by executing a concept search with an inquiry text from a customer specified for search criteria as is.